Method

In bowl, whisk egg; whisk in onion, mustard, Worcestershire sauce, barbecue sauce, water, salt and pepper. Mix in beef. Form by 1/4 cups (50 mL) into twelve 1/4-inch (5 mm) thick patties. (Make-ahead: Layer between waxed paper in airtight container and refrigerate for up to 24 hours. Or freeze for up to 4 weeks; thaw in refrigerator.)

In large heavy skillet, heat half of the oil over medium-high heat; fry burgers, in batches, turning once and adding remaining oil as necessary, until thermometer inserted sideways into patty reads 160°F (71°C), about 8 minutes. (Make-ahead: Let cool; cover and refrigerate for up to 24 hours. Reheat on rimmed baking sheet in 350°F/180°C oven for 10 minutes.)